Anti-obesity composition containing acacia bark derivative

ABSTRACT

It is intended to provide a composition having an excellent anti-obesity action without potential for adverse side effects and the like even if taken for a long period of time. The composition is an anti-obesity composition containing an  acacia  bark derivative.

TECHNICAL FIELD

The present invention relates to an anti-obesity composition derivedfrom a tree belonging to the genus Acacia, and to uses as a food, ananimal feed material, a medicine and a quasi-drug containing thisanti-obesity composition.

BACKGROUND ART

In general, obesity refers to a condition of excess accumulation offatty tissue in the body. Body mass index (BMI), which is adopted in ahealth check up, etc., is determined by dividing body weight (kg) by thesquare of height (m). Body weight for which BMI is 22 is referred to asstandard body weight, and a body weight that is 10% or more higher thanthe standard body weight is referred to as being overweight, while abody weight that is 20% or more higher than the standard body weight isreferred to as obesity. The number of obese persons and persons whowould become obese has increased in recent years due to Westernizationof the diet, a lack of exercise resulting from the development oftransportation facilities and the like. In particular, obesity isclosely correlated with the onset of diseases such as hypertension,diabetes, fatty liver, arteriosclerosis, stroke, hyperlipemia,peripheral circulatory disorders and ischemic heart disease, and theprevention or decrease of obesity is extremely important from theviewpoint of preventing and treating the onset of these diseases.

Although improvement of lifestyle in terms of diet therapy and exercisetherapy is desirable for preventing or decreasing obesity, this cannotalways be easily achieved. In addition, although drug therapy isavailable for the treatment of obesity, including the use of lipidabsorption inhibitors and intestinal absorption inhibitors, their use islimited to cases of serious obesity.

Amidst these circumstances, various products using natural ingredientshaving various actions and having less potential for adverse sideeffects and the like even if taken for a long period have been soldcommercially in the form of a diet food and the like for the purpose ofpreventing or decreasing obesity, and searches are being made for novelsubstances having an anti-obesity activity.

For example, Patent Document 1 discloses that a dried powder, extract orpurified product of Kouki leaves or bark has a weight loss effect onrats and humans. In addition, Patent Document 2 discloses that tannin, akind of polyphenol has α-amylase inhibitory effects and anti-obesityeffects.

On the other hand, with respect to acacia acacia honey is known, andtannin which is extracted from bark thereof is known to be able to beused as a tanning agent or a wood adhesive, while more recently,extracts of genus Acacia have been disclosed to have selectiveinhibitory effects on COX-2 (Patent Document 3), and bark of genusAcacia has been disclosed to have active oxygen eliminating effects(Patent Document 4) and skin whitening effects due to the effect ofinhibiting tyrosinase activity (Patent Document 5). However, acacia barkand polyphenols derived from acacia bark have heretofore not been knownto have an anti-obesity action.

[Patent Document 1] JP2004-091464A

[Patent Document 2] JP2002-051735A

[Patent Document 3] JP2004-532811A

[Patent Document 4] JP2004-352639A

[Patent Document 5] JP10-025238A

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

An object of the present invention is to provide a composition having anexcellent anti-obesity action without potential for adverse side effectsand the like even if taken for a long period of time.

Means for Solving the Problems

As a result of conducting extensive studies to solve the above problems,the inventors of the present invention found that an acacia barkderivative has an anti-obesity action to be useful for the prevention,decrease or treatment of obesity, thereby leading to the completion ofthe present invention.

Namely, the present invention relates to an anti-obesity compositioncontaining an acacia bark derivative(s).

In addition, the present invention also relates to a method forpreventing or treating obesity using an acacia bark derivative(s).

Moreover, the present invention relates to a method for using an acaciabark derivative(s) for producing a composition for preventing ortreating obesity.

Effects of the Invention

According to the present invention, a composition having an anti-obesityaction can be provided.

Moreover, according to the present invention, a composition is providedwhich is safe and has less potential for adverse side effects and thelike even if taken for a long period of time.

BEST MODE FOR CARRYING OUT THE INVENTION

There are no particular limitations on the acacia bark derivative ableto be used in the present invention provided that it is obtained byusing as a raw material bark of a tree belonging to the genus Acacia(the tree is referred to as “acacia” or “genus Acacia” hereinafter),examples of which derivatives include a strip and a powder of acaciabark, and a suspension thereof, an extract such as a liquid extract, aconcentrated liquid extract and a powdered extract of acacia bark, and apurified product obtained by purifying these extracts. The extract ofacacia bark and particularly acacia bark polyphenols are preferable forproduction of excellent anti-obesity activity.

In the present invention, only a single form of these acacia barkderivatives may be used, or alternatively two or more forms thereof maybe used in combination.

Although there are no particular limitations on acacia able to be usedin the present invention so long as it is a tree belonging to the genusAcacia, with respect to obtaining an acacia bark derivative having anexcellent anti-obesity action, bark of the genus Acacia selected fromthe group consisting of scientific name: Acacia mearnsii De Wild.(generic name: black wattle), scientific name: Acacia mangium Willd.(generic name: acacia mangium), scientific name: Acacia dealbata Link,scientific name: Acacia decurrens Willd. and scientific name: Acaciapycnantha Benth. are preferable, while Acacia mearnsii De Wild. andAcacia mangium Willd. are particularly preferable.

In the present invention, only a single type of these acacia bark may beused, or alternatively two or more forms thereof may be used incombination.

The aforementioned acacia bark can normally be obtained by cutting downan acacia tree, pealing off only bark and then drying the bark morepreferably by sun-drying.

Bark of acacia is comprised of an outer bark and a somewhat fibrousinner bark, and when dried to a moisture content of about 20% or less,can be easily finely pulverized with a size reduction mill such as ahammer mill. In the present invention, both the outer bark and innerbark of the genus Acacia may be used together or either one may be usedalone as the acacia bark.

The aforementioned strip of acacia bark can be obtained in accordancewith commonly used methods by pulverizing the acacia bark to a suitablesize.

In addition, although the aforementioned powder of acacia bark can beobtained by pulverizing the acacia bark into a powder in accordance withcommonly used methods, in particular, the particle diameter of theresulting powder is preferably 100 μm or less and particularlypreferably 50 to 70 μm. Powder fractionation can be carried out bypulverizing the bark dried to a moisture content of 20% or less to asuitable size such as a particle diameter of about 1.6 mm or less, andthen classifying the resulting powder with a vibrating screen or thelike to obtain the required powder.

The aforementioned extract of acacia bark can be obtained by extractionfrom the acacia bark in accordance with commonly used methods. In orderto obtain an extract of acacia bark having an excellent anti-obesityaction, it is preferably extracted from the acacia bark with an alcoholor a polar solvent.

Ethanol, etc. can be used as the alcohol, and water, etc. can be used asthe polar solvent, and these solvents may be used singly or incombination of two or more kinds as necessary. A mixed solvent of waterand the alcohol such as ethyl alcohol is particularly preferable forproduction of an excellent anti-obesity action.

Moreover, the extraction procedure may be carried out a number of timesusing the same or different solvents.

In terms of obtaining an extract having an excellent anti-obesityaction, an extract which is obtained from the acacia bark by extractionwith water or hot water, and then further extraction from the resultingextract with ethanol may be used.

Although the extraction is carried out by adding the solvent to a strip,a powder or the like of the acacia bark followed by stirring asnecessary, there are no particular limitations on temperature, time orsolid-liquid ratio. In the case of using water as the solvent, theextraction may also be carried out with hot water. The resulting liquidextract may be freeze-dried or spray-dried directly, or may befreeze-dried or spray-dried after concentrating under reduced pressure.The resulting extract can be in various forms, such as a liquid extract,solution, powder, concentrate or paste, and can be used in a wide rangeof forms as necessary.

Moreover, the acacia bark extract of the present invention obtained inany of these forms can be used directly as a anti-obesity composition,or a purified product obtained by purifying the extract as necessary canalso be used as a anti-obesity ingredient.

In the present invention, ingredients contained in bark of the genusAcacia are also examples of the acacia bark derivatives. Examples ofsuch ingredients are the acacia hark polyphenols. The acacia barkpolyphenols are particularly preferable ingredients since they produceexcellent anti-obesity action.

The acacia bark polyphenols of the present invention refer to a type ofcondensed tannins in the form of polymers in which flavanols having as abasic skeleton flavan-3-ol such as (−)-fisetinidol, (−)-robinetinidol,(+)-catechin and (+)-gallocatechin are linked by C4-C8 or C4-C6 bonds.Here, the molecular weights of such condensed tannins are preferably 300to 3000 and particularly preferably 500 to 3000. The acacia barkpolyphenols used in the present invention can be obtained from thepowder, etc. of the acacia bark by extracting with hot water aspreviously described.

In addition, examples of commercially available acacia bark polyphenolsinclude MIMOSA ME POWDER, MIMOSA MS POWDER, MIMOSA GS POWDER, MIMOSA FSPOWDER, MIMOSA WS POWDER, MIMOSA RG POWDER, MIMOSA RN POWDER, MIMOSA DKPOWDER, MIMOSA AL POWDER, MIMOSA CR POWDER and GOLDEN MIMOSA POWDER (allregistered trademarks) which are manufactured by Mimosa CentralCo-operative Ltd., and the like.

An anti-obesity action as referred to in the present invention refers toaction that reduces or suppresses body weight or the amount, weight orconcentration of body fat by ingesting a certain substance into the bodyas compared with not ingesting that substance.

Body fat as used in the present invention includes subcutaneous fat andvisceral fat formed due to the accumulation of fat in fat cells, as wellas cholesterol, neutral fats (triglycerides), phospholipids and freefatty acids present in the blood.

Although the composition of the present invention may be the acacia barkderivative(s) such as the acacia bark, the extract(s) thereof, thepurified product(s) thereof or the acacia bark polyphenol(s) per se, itmay also contain other substance(s) having an anti-obesity action, suchas flavonoid(s) contained in a plantain.

Although the composition of the present invention may be the acaciabark, the extract(s) thereof, the purified product(s) thereof or theacacia bark polyphenol(s) per se, it may contain vehicles, sweeteners,sour flavorings, thickeners, fragrances, pigments, emulsifiers, andother materials which are ordinarily used in foods, so long as they donot undermine the effects of the present invention.

The composition according to the present invention can be used as a foodor an animal feed material, for example, as a health food, a functionalfood, a health supplement food, a food for specified health use, abeauty food or a nutritional supplement food (supplement) for purposessuch as preventing or decreasing obesity. For example, these foods oranimal feed material may also be in the form of a beverage such as teaor juice; ice cream, jelly, candy, chocolate or chewing gum, etc. Inaddition, they may also be in the form of liquids, powders, granules,capsules or tablets. Here, animals fed by the animal feed materialinclude all animals requiring the prevention, decrease or treatment ofobesity, including pets, livestock or animals bred at zoos, etc.

In addition, the composition according to the present invention can beused as a medicine or a quasi-drug for the prevention, decrease,treatment or the like of obesity. These medicines and drugs can beadministered, for example, orally in the form of tablets, coatedtablets, sugar coated pills, hard or soft gelatin capsules, liquids,emulsions or suspensions.

There are no particular limitations on an ingested amount of thecomposition according to the present invention, and the ingested amountcan be suitably selected depending on the dosage form as well as theage, body weight and symptoms of an ingesting person such as a user orpatient, or an ingesting animal. For example, it is desired that theingesting person or ingesting animal orally ingests an amount of theacacia bark polyphenol(s) ranging from 0.001 to 1 g, preferably from0.001 to 0.5 g and more preferably from 0.005 to 0.1 g per 1 kg of bodyweight per day in terms of the amount of active ingredient, since itproduces an excellent anti-obesity action.

The duration of ingestion can be arbitrarily determined depending on theage and symptoms of the user or patient.

Although the following provides a more detailed explanation of thepresent invention through examples thereof, the present invention is notlimited thereto.

EXAMPLES

Although the following provides a more detailed explanation of thepresent invention through production examples, test examples andformulation examples thereof, the present invention is not limitedthereto. In particular, although the following examples are indicatedwithout making a distinction between the outer bark and inner bark ofthe acacia bark of the present invention, the outer bark can beseparated from the inner bark and each can also be used, separately.

In the following production examples, test examples and the like, eachacacia of the present invention is indicated with numbers shown inparentheses after each scientific name. For example, acacia known by thescientific name of Acacia mearnsii De wild. is indicated as Acacia No.1.

Scientific name: Acacia mearnsii De Wild. (No. 1), scientific name:Acacia mangium Willd. (No. 2), scientific name: Acacia dealbata Link(No. 3), scientific name: Acacia decurrens Willd. (No. 4), scientificname: Acacia pycnantha Benth. (No. 5).

In addition, percentages (%) refer to percent by weight (wt %) unlessspecifically indicated otherwise.

Production Example 1 Acacia Bark Powder

Bark of Acacia No. 1 was dried to a moisture content of 20% or less andafter pulverizing the dried bark in a hammer mill to a powder having aparticle diameter of 1.6 mm or less (the powder passing through a 10mesh Tyler screen), the powder was further classified with a vibratingscreen to obtain a fine powder having a particle diameter of 63 μm orless (passing through a 250 mesh screen).

Fine powders each having a particle diameter of 63 μm or less weresimilarly obtained by pulverizing bark of the remaining four types ofacacia namely Acacia No. 2 to Acacia No. 5. Although there were somedifferences in the efficiency by which the fine powder passed throughthe 250 mesh screen depending on the type, all of the target finepowders were able to be obtained.

Production Example 2 Acacia Bark Extract

Bark of each Acacia No. 1 to 5 of the present invention was dried to amoisture content of 20% or less and after pulverizing the dried bark ina hammer mill to a powder having a particle diameter of 1.6 mm or less,five times the amount of hot water were added to 100 g of the driedpulverized bark followed by extraction for 15 minutes after boiling, andthen filtering using a 10 to 20 μm filter. The resulting filtrate wasspray-dried in a spray dryer to obtain 40 g of each bark extract.

The bark extracts are hereinafter indicated as Acacia Hot Water ExtractsNos. 1 to 5, respectively.

Production Example 3 Acacia Bark Extract

Acacia bark of the present invention was dried to a moisture content of20% or less and after pulverizing the dried bark in a hammer mill to apowder having a particle diameter of 1.6 mm or less, five times theamount of ethanol were added to 100 g of the dried pulverized barkfollowed by extraction for 15 minutes while refluxing after boiling, andthen filtering using a 10 to 20 μm filter. After evaporating the ethanolfrom the resulting filtrate, the concentrate was spray-dried in a closedspray dryer to obtain 40 g of bark extract (to be indicated hereinafterin the manner of Acacia Ethanol Extract No. 1).

Acacia Ethanol Extracts Nos. 1 to 5 were obtained in the same manner.

Production Example 4 Acacia Bark Extract

Three times the amount of ethanol were added to 10 g of the acacia hotwater extract obtained in Production Example 2 followed by extractionfor 15 minutes while refluxing after boiling, and then filtering using a10 to 20 μm filter. The ethanol was evaporated from the resultingfiltrate, water was added thereto, and then freeze-dried to obtain 9 gof extract (to be indicated hereinafter in the manner of Acacia HotWater Extract Ethanol Fraction No. 1).

Acacia Hot Water Extract Ethanol fractions Nos. 1 to 5 were obtained inthe same manner.

Test Example 1 Anti-Obesity Test Using Rat High-Fat Diet Loading Model

1. Test Method

Feed containing 5% of Acacia Hot Water Extract No. 1 described inProduction Example 2 and 20% of lard was fed to rats (Slc:SD, males, age5 weeks) for 56 days. A control group was given feed mixed with 20%lard.

Weekly water and food consumption were measured once a week followed bycalculating the amounts consumed per day.

Triglyceride levels and other blood biochemical values were measured onthe day following the final day of dosing using an automated analyzer(Model 7170, Hitachi Instrument Engineering Co., Ltd.). The rats werenot fed on the day before. In addition, all visceral fat was excisedfrom the abdominal cavity followed by measuring the absolute weightthereof while also calculating the relative weight (per 100 g of bodyweight).

Each of the resulting measured values was expressed as the mean±standarderror. Testing for the presence of a significant difference from thecontrol group was carried out using the Student's t-test in the presenceof a uniform distribution as determined with the F test, or carried outusing the Aspin-Welch t-test in the absence of a uniform distribution asdetermined with the F test. The level of significance was indicated as5% or 1%.

2. Test Results

The results are shown in the following Tables 1 to 4, None of the ratsdied or demonstrated abnormalities in general condition.

TABLE 1 Body Weight (g) No. of Measurement weeks Dose group animalsBefore dosing Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 7 Week 8Control group 7 136 ± 5 205 ± 6 271 ± 7 326 ± 8 373 ± 9 418 ± 10 456 ±12 493 ± 13 529 ± 13 Acacia Hot Water 7 137 ± 5 169 ± 5** 218 ± 9** 249± 9** 300 ± 9** 351 ± 14** 387 ± 17** 419 ± 19** 452 ± 20** Extract No.1 **p < 0.01

TABLE 2 Food Consumption (g/day) No. of Measurement weeks Dose groupanimals Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 7 Week 8 Controlgroup 7 22.0 ± 0.7  22.7 ± 0.4 23.0 ± 0.4 23.2 ± 0.5 25.1 ± 0.5 23.4 ±0.8 24.5 ± 0.7 23.8 ± 0.5 Acacia Hot Water 7 17.4 ± 0.5** 23.8 ± 1.021.7 ± 0.7 24.0 ± 1.0 25.4 ± 1.7 23.4 ± 1.7 22.8 ± 1.5 23.4 ± 1.3Extract No. 1 **p < 0.01

TABLE 3 Water Consumption (mL/day) No. of Measurement weeks Dose groupanimals Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 7 Week 8 Controlgroup 7 21.1 ± 1.3 22.1 ± 1.5 23.3 ± 1.0 22.8 ± 1.4 25.2 ± 1.8 26.5 ±2.1 27.5 ± 2.1 29.5 ± 2.8 Acacia Hot Water 7 20.3 ± 0.8 23.6 ± 1.2 23.9± 1.3 26.6 ± 1.6 27.3 ± 2.4 26.9 ± 2.1 26.9 ± 1.9 27.5 ± 1.8 Extract No.1

TABLE 4 Visceral Fat Weight and Blood Biochemistry Tests No. of Visceralfat weight T-CHO TG Phospholipids Free fatty acids Ketones Dose groupanimals g g/100 g mg/dL mg/dL mg/dL μEq/L μmol/L Control group 7 46.5 ±3.8 9.2 ± 0.6 56 ± 6 70 ± 10 103 ± 6  446 ± 95 1399 ± 104 Acacia HotWater 7 24.1 ± 3.6** 5.5 ± 0.6** 49 ± 1 37 ± 5* 88 ± 2* 324 ± 30 1217 ±221 Extract No. 1 *p < 0.05 **p < 0.01

Visceral fat weights, triglyceride levels, phospholipid levels and bodyweights in the Acacia Hot Water Extract No. 1 dose group decreased incomparison with the control group.

Since there were no differences observed for food consumption and waterconsumption, the above decreases were thought to be attributable to theadministration of Acacia Hot Water Extract No. 1.

On the basis of these results, body fat decreased significantly as aresult of the administration of the acacia bark extract.

Test Example 2 Body Fat Reduction Test Using Rat High-Fat Diet LoadingModel

1. Test Method

Mixed feed respectively containing 0.5%, 1.5% and 5.0% of Acacia HotWater Extract No. 1 (Each feed contained 20% of lard) was fed for 56days to rats (Slc:SD, males, age 5 weeks). A control group was givenfeed mixed with 20% of lard.

Each parameter was measured in the same manner as in Test Example 1.

The resulting measured values were expressed as the mean±standard error.Testing for the presence of a significant difference between the controlgroup and the Acacia Hot Water Extract No. 1 dose groups was carried outusing Dunnett's multiple comparison test. The level of significance wasindicated as 5% or 1%.

2. Test Results

The results are shown in the following Tables 5 to 8, None of the ratsdied or demonstrated abnormalities in general condition.

TABLE 5 Body Weight (g) Measurement weeks No. of Before Dose groupanimals dosing Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 7 Week 8Control group 10 142 ± 7 204 ± 13 261 ± 18 313 ± 23 358 ± 26 400 ± 23437 ± 24 468 ± 25 495 ± 25 Acacia Hot 10 140 ± 7 199 ± 13 257 ± 18 310 ±23 354 ± 27 394 ± 27 422 ± 34 465 ± 38 492 ± 37 Water Extract No. 1 0.5%dose group Acacia Hot 10 141 ± 6 194 ± 12 252 ± 20 298 ± 26 340 ± 35 379± 35 412 ± 37 438 ± 38 464 ± 45 Water Extract No. 1 1.5% dose groupAcacia Hot 10 142 ± 8 168 ± 7** 210 ± 14** 251 ± 19** 287 ± 24** 325 ±24** 357 ± 25** 383 ± 24** 408 ± 24** Water Extract No. 1 5.0% dosegroup **P < 0.01; significant difference versus value of control group(Dunnett's multiple comparison)

TABLE 6 Food Consumption (g/day) No. of Measurement weeks Dose groupanimals Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 7 Week 8 Controlgroup 10 21.1 ± 1.7 22.0 ± 1.8 25.2 ± 2.8 20.4 ± 2.1 22.6 ± 2.3 22.0 ±2.0 21.7 ± 2.2 21.4 ± 1.7 Acacia Hot Water 10 21.5 ± 2.8 22.7 ± 1.4 24.8± 3.5 21.2 ± 2.6 22.3 ± 2.8 22.9 ± 1.7 22.5 ± 2.7 21.9 ± 2.8 Extract No.1 0.5% dose group Acacia Hot Water 10 22.6 ± 3.0 26.6 ± 5.9* 27.3 ± 4.322.6 ± 2.5 24.0 ± 2.6 24.9 ± 4.4 25.1 ± 5.3 25.0 ± 4.3 Extract No. 11.5% dose group Acacia Hot Water 10 19.7 ± 2.8 26.7 ± 4.9* 27.5 ± 3.623.4 ± 4.0 26.2 ± 2.8** 24.5 ± 3.3 24.6 ± 3.9 27.0 ± 4.5** Extract No. 15.0% dose group *P < 0.05, **P < 0.01; significant difference versusvalue of control group (Dunnett's multiple comparison)

TABLE 7 Water Consumption (mg/day) No. of Measurement weeks Dose groupanimals Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 7 Week 8 Controlgroup 10 21.0 ± 2.4 22.6 ± 3.4 24.0 ± 4.2 23.9 ± 6.1 25.1 ± 7.2 24.8 ±4.3 25.0 ± 4.9 26.5 ± 7.6 Acacia Hot Water Extract 10 20.3 ± 2.6 22.2 ±3.2 23.7 ± 3.7 26.0 ± 6.9 26.4 ± 5.7 28.5 ± 6.0 30.8 ± 8.8 30.6 ± 11.1No. 1 0.5% dose group Acacia Hot Water Extract 10 21.5 ± 2.6 23.6 ± 3.323.8 ± 3.8 24.0 ± 4.0 24.1 ± 3.7 24.7 ± 3.7 27.2 ± 7.9 24.9 ± 4.6 No. 11.5% dose group Acacia Hot Water Extract 10 20.3 ± 4.2 22.5 ± 2.8 24.4 ±5.7 24.1 ± 3.6 25.4 ± 4.1 24.0 ± 3.7 23.2 ± 3.0 22.5 ± 2.9 No. 1 5.0%dose group

TABLE 8 Visceral Fat Weight and Blood Biochemistry Tests Visceral fatweight No. of g/body T-CHO TG Phospholipids Free fatty acids KetonesDose group animals g weight 100 g mg/dL mg/dL mg/dL μEq/L μmol/L Controlgroup 10 38.6 ± 8.8 8.0 ± 1.6 66.0 ± 12.0 74.0 ± 21.0 111.0 ± 13.0 661.0± 54.0 1094 ± 537 Acacia Hot Water Extract 10 36.7 ± 7.4 7.7 ± 1.1 53.0± 17.0 74.0 ± 21.0 101.0 ± 11.0 704.0 ± 104.0 1094 ± 307 No. 1 0.5% dosegroup Acacia Hot Water Extract 10 29.6 ± 8.9* 6.5 ± 1.4* 53.0 ± 7.0*62.0 ± 14.0  94.0 ± 8.0** 620.0 ± 124.0 1535 ± 273 No. 1 1.5% dose groupAcacia Hot Water Extract 10 19.5 ± 6.3** 4.9 ± 1.4** 55.0 ± 9.0 39.0 ±14.0**  89.0 ± 9.0** 604.0 ± 148.0 1801 ± 418** No. 1 5.0% dose group *P< 0.05, **P < 0.01; significant difference versus value of control group(Dunnett's multiple comparison)

Triglyceride levels and phospholipid levels decreased significantly inthe extract dose groups and absorption of fat was suppressed. Sinceketone levels increased in the Acacia Hot Water Extract No. 1 dosegroups, this can be expected to also have the effect of suppressingaccumulation of fat in the body.

On the basis of these results, Acacia Hot Water Extract No. 1 was shownto reduce body fat.

Test Example 3 Mutagenicity Test

A mutagenicity test was conducted in compliance with Ministry of Health,Labor and Welfare Notification No. 77 (Sep. 1, 1988). As a result oftesting with test substance (Acacia Hot Water Extracts Nos. 1 to 5 ofProduction Example 2) at doses of 156 to 5,000 μg/plate, there were noincreases in the numbers of revertant colonies for any of the bacterialstrains.

Test Example 4 Micronucleus Test

The presence of the ability to induce micronuclei was investigated invivo in accordance with ordinary methods. Acacia Hot Water Extract No. 1was orally administered twice at 24-hour intervals at daily doses of2,000, 1,000 and 500 mg/kg to male ICR mice followed by the preparationof micronucleus specimens 24 hours after the final dosing. Acacia HotWater Extract No. 1 did not demonstrate positive results at any of thedose levels. In addition, there were no constant fluctuations in thesimultaneously observed ratio of total polychromatic erythrocytes tototal erythrocytes, and inhibition of erythrocyte. proliferation was notobserved in comparisons with a negative control group.

Test Example 5 Mouse Acute Toxicity Study (Oral Administration)

An acute oral dose toxicity study was conducted using male and femaleICR mice in compliance with OECD (Guidelines for the Testing ofChemicals, 401, 1987). As a result, the LD₅₀ value of Acacia Hot WaterExtract No. 1 was 4,468 mg/kg among males and 3,594 mg/kg among females.

Similar results were obtained in the above study for Acacia Hot WaterExtracts Nos. 2 to 5 of Production Example 2.

Test Example 6 Rat Repeated Dose Toxicity Study (Oral Administration)

A 13-week repeated dose toxicity study was conducted using rats inaccordance with ordinary methods. Mixed feed containing 0.5, 1.5 and5.0% of Acacia Hot Water Extract No. 1 was fed to male and female Slc:SDrats.

As a result, none of the rats died or demonstrated abnormalities inexaminations, including general condition.

Test Example 7 Human Single Dose Study

Five healthy adult males age 32 to 43 years were given 1500 mg of AcaciaHot Water Extract No. 1 (12 tablets of Formulation Example 4 describedbelow). Although general examinations, hematology tests, bloodbiochemistry tests and urinalyses were performed on the subjects beforeingestion, 3 hours after ingestion, 8 hours after ingestion, 24 hoursafter ingestion and 1 week after ingestion, there were no clinicallysignificant fluctuations in test values. There were also no adverseevents attributable to the tablets.

Test Example 8 Human 4-Week Continuous Dosing Study

Twenty-five healthy adult males age 23 to 44 years were given Acacia HotWater Extract No. 1 of Formulation Example 4 described below at 750mg/day (6 tablets of Formulation Example 4) and 1000 mg/day (8 tabletsof Formulation Example 4) for 4 weeks each.

General examinations, hematology tests and urinalyses were performed onthe subjects of each group before ingestion, 2 weeks after ingestion, 4weeks after ingestion and 2 weeks following completion of ingestion.There were no clinically significant fluctuations in test values. Therewere also no adverse events.

Formulation Example 1 Preparation of Internal Medication

An internal medication having the composition indicated below wasprepared using the acacia bark Hot Water Extract Ethanol Fraction ofProduction Example 4,

Extract fraction of Production Example 4 1.0 (wt %) Lactose 30.0Cornstarch 60.0 Crystalline cellulose 8.0 Polyvinyl pyrrolidone 1.0Total 100.0

Formulation Example 2 Preparation of Pet Food

A pet food having the composition indicated below was prepared using theacacia bark Hot Water Extract of Production Example 2,

Extract of Production Example 2 1.0 (wt %) Oatmeal 88.0 Starch 5.0 Salt2.5 Whole egg 3.0 Flavoring 0.5 Total 100.0

Formulation Example 3 Preparation of Tablets (Confections)

Tablets (confections) having the composition indicated below wereprepared using the acacia bark Hot Water Extract Ethanol Fraction ofProduction Example 4,

Extract fraction of Production Example 4 1.0 (wt %) Citric acid 1.0Powdered skim milk 15.0 Sucrose ester 1.0 Flavoring 0.5 Powdered sugar20.0 Lactose 61.5 Total 100.0

Formulation Example 4 Preparation of Tablets

Tablets having the composition indicated below were prepared usingAcacia Bark Hot Water Extract No. 1 of Production Example 2,

Acacia Bark Hot Water Extract No. 1 of 125 (mg) Production Example 2Sucrose ester 9 Lactose 166 Total 300

INDUSTRIAL APPLICABILITY

The anti-obesity composition of the present invention is thought to beable to be used as a medicine or a food such as a health food, a healthsupplement food, a food for specified health use or a nutritionalsupplement food for use in preventing, decreasing and/or treatingobesity. Moreover, it is also expected to be able to be used for theprevention and treatment of hypertension, diabetes, fatty liver,arteriosclerosis, stroke, hyperlipemia, peripheral circulatory disordersand ischeric heart disease.

The invention claimed is:
 1. A method of suppressing the accumulation ofbody fat in a subject which comprises: administering to a subject inneed thereof an anti-obesity composition comprising: (a) a hot waterextract(s) of at least one acacia bark, wherein the acacia bark isobtained from at least one of Acacia mearnsii De Wild., Acacia mangiumWilld., Acacia dealbata Link, Acacia decurrens Willd. and Acaciapycnantha Benth, and the hot water extract of acacia bark is apolyphenol; wherein the hot water extract(s) of acacia bark contains anacacia bark polyphenol(s), wherein the polyphenol(s) is a condensedtannin(s) having a molecular weight(s) of 500 to 3000, and is apolymer(s) of flavanols having flavan-3-ol as a basic skeleton linked byC4-C8 or C4-C6 bonds, and said flavan-3-ol is selected from the groupconsisting of (−)-fisetinidol, (−)-robinetinidol, (+)-catechin and(+)-gallocatechin, and at least one of vehicles, sweeteners, flavorings,thickeners, fragrances, pigments, emulsifiers, a food, a feed material,and a medicine; wherein the subject is a person or an animal with a highfat diet; and the composition contains an effective amount of the hotwater extract of at least one acacia bark to suppress accumulation ofbody fat in the subject.
 2. The method according to claim 1, wherein theacacia bark is a bark of Acacia mearnsii De Wild.
 3. The methodaccording to claim 1, wherein the acacia bark polyphenol(s) is orallyingested by the subject at 0.001 to 1 g per kg of body weight per day interms of the amount of active ingredient.
 4. The method according toclaim 1, wherein the composition is in the form of a food, an animalfeed material, or a medicine.
 5. The method according to claim 1,wherein the effective amount of the hot water extract of at least oneacacia bark is an amount of 0.001 to 1 g per kg of body weight per dayin terms of the amount of active ingredient.
 6. The method according toclaim 5, wherein the effective amount of the hot water extract of atleast one acacia bark is an amount of 0.001 to 0.5 g per kg of bodyweight per day in terms of the amount of active ingredient.